Random bytes are added when sending files using C++ Sockets - c++

Question

When I send a file using C++ Socket, random bytes are added at the beginning. The problem occurs every few attemps. I tried to clear the buffers using different ways but nothing worked so far. I also noticed that in the received file i can see strings such as "File Size is".
I m using 2 Docker containers, each runs Ubuntu 20.04 LTS.
This is the code i use to send the files:
int Socket::send_file(string path,int socket_){
if (socket_ == -1 )
{
socket_ = clientSd ;
}
ifstream fichier ;
fichier.open(path,ios::in | ios::binary);
if (fichier.is_open())
{
cout << "File Opened " << endl ;
}else
{
cout << "Failed to open file " << endl ;
exit(0);
}
int size = get_file_size(fichier);
fichier.close();
char msg[MAX_BUFFER];
sprintf(msg, "%d\0", size);
cout << "File Size is " << size << endl ;
send(socket_, (char*)msg, sizeof(msg) , 0); // 2
char buffer[MAX_BUFFER]; // 4222111
const char *c = path.c_str();
sprintf(buffer, "%d\0", size);
FILE *fd = fopen(c, "rb");
size_t rret, wret;
int bytes_read;
int fragment = MAX_BUFFER ;
while (!feof(fd)) {
if ((bytes_read = fread(&buffer, 1, MAX_BUFFER, fd)) > 0)
send(socket_, buffer, bytes_read, 0);
else
break;
}
fclose(fd);
cout << "End" << endl ;
return 1 ;
}
This is the code i use to receive the files:
int Socket::receive_file(string path,int socket_){
if (socket_ == -1 )
{
socket_ = clientSd ;
}
char* buffer ;
buffer = (char*) malloc(sizeof(char) * MAX_BUFFER) ;
recv(socket_, (char*)buffer, MAX_BUFFER, 0); // 3
int size = atoi(buffer) ;
cout << "File Size is " << size << endl ;
size_t datasize;
char text[MAX_BUFFER]; // 1024
const char *c = path.c_str();
FILE* fd = fopen(c, "wb");
int received = 0 ;
while (received < size)
{
datasize = recv(socket_, text, sizeof(text), 0);
fwrite(&text, 1, datasize, fd);
}
fclose(fd);
cout << "End" << endl ;
return 1 ;
}